1. Field of the Invention
The present invention relates to a coloring matter compound, and an ink, a resist composition for a color filter and a heat-sensitive transfer recording sheet all containing the coloring matter compound.
2. Description of the Related Art
Recently, there have been increasing demands for image quality improvement for color images in a color liquid crystal display and the like. A color filter is indispensable for color display in a liquid crystal display and is a significant component that affects the performance of the liquid crystal display. As a conventional method for producing a color filter, a dyeing method, a printing method, an inkjet method, and a photoresist method, are known. Among these methods, production by the photoresist method is principally employed because in this method, spectral properties and color reproducibility can be easily controlled and resolution is so high that high resolution patterning can be performed.
In the photoresist method, a pigment has been generally used as a coloring agent, but there are a large number of problems such as depolarization (namely, disturbance of polarization), lowering of a contrast ratio in color display in a liquid crystal display, lowering of brightness of a color filter, and stabilization of dispersion in an organic solvent or a polymer. Therefore, attention is now being paid to a production method using a dye. For example, in order that an image with good spectral properties and a high display contrast can be displayed, a color filter using, as a coloring agent, a xanthene coloring matter has been reported (see Japanese Patent Application Laid-Open No. 2003-344998). In order to display an image with higher resolution, however, it is desired to develop a color filter with strong light resistance and good spectral properties.
Moreover, coloring matter compounds are desired to be improved in fields other than the field of color filters. An example of such fields includes a field of an image formation method employing a heat-sensitive transfer recording method.
The heat-sensitive transfer recording method is an image formation method by which recording is performed as follows: A heat-sensitive transfer sheet formed on a sheet-shaped substrate and including a coloring material layer containing a thermally migratory coloring matter is overlaid on an image receiving sheet having, on a surface thereof, a coloring matter receiving layer, and the heat-sensitive transfer sheet is heated so as to transfer the coloring matter contained in the heat-sensitive transfer sheet onto the image receiving sheet. In this heat-sensitive transfer recording method, a coloring matter compound contained in a transfer sheet and an ink composition for the transfer sheet is an extremely significant material because this compound affects the speed of the transfer recording, image quality of recorded products, and storage stability. As a coloring matter to be used in this heat-sensitive transfer recording method, use of methine coloring matters excellent in clarity, color reproducibility, coloring density and the like has been reported (see International Patent Application No. WO 92/19684 and Japanese Patent Application Laid-Open No. H05-262062). If the methine coloring matter is used in a high density, however, there arose problems of saturation lowering caused by the aggregation of the coloring matter itself and of low light resistance. Therefore, it is desired, even now, to develop a coloring matter compound that has high saturation in a high density region and is excellent in light resistance.